New binary file format #6
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The new format has an 8-byte header (count) followed by the elements data.
Each element is represented by a 4-byte header and a data section.
The 4-byte header contains the size of the data section.
The data section is the raw data (no serialization).
Example of a score file with 2 elements ("hello" and "world"):
0x0002 0x05 hello 0x05 world
count size data size data
2 5 "hello" 5 "world"
The extra `seek()` calls were a performance regression
After the binary format for zsets, the JSON serialization became useless
This is for consistency and to help in the future Python 3 migration
Try to read the number of elements found in the file header instead of checking if 0 bytes were returned when reading
All these methods now share the file object (instance attribute)
Before the binary file manipulation, special unicode characters were not handled well
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Backward incompatibility
This branch has backward incompatible changes to the file formats of every data structure. There's no longer JSON serialization.
New sorted set binary format
The sorted set file structure is the one with the most changes focusing on optimization. The new structure uses a binary format to store how many entries there are in each score file and also the size of each element before the element data.
I picked 8 bytes for the header because that gives us 2**64 capacity on each sorted set. I also picked 4 bytes for the data size because that gives each element 4GB of space.
The optimization results are approximately the following:
I've seen a ~5% time variation in performance test times on my laptop, please take that into account (the results are still very significant).